Heating system



Nov. 30, 1943. R E, Mock-g 2,335,785

HEATING SYSTEM 1 Filed July s, 1941 2 Sheets-S heet 1 R. E. MOORE HEATING sysmm Filed July 3, 1941 '2 Sheets-Sheet 2 Patented Nov. 30,; 1943 UNITED STATES PATENT OFFICE HEATING SYSTEM Robert Edwin Moore, Park Ridge, 111.

Application July 3, 1941, Serial No. 400,999

26 Claims.

My invention relates to continuously heated, hot water heating systems of the closed typ such as those which are hand or stoker fired, and is concerned primarily with an arrangement for preventing the boiler water from reaching an excessive temperature to thereby protect the boiler and auxiliary devices and controls.

In heating systems of the type indicated, the boiler water is subjected to continuous heat, as

distinguished from the intermittent firing of gas or oil fired boilers in which the burner is readily controlled by a boiler aquastat. It has been ascertained that, notwithstanding that a continuously heated system may be provided with a relief valve that relieves water to a drain when the gage pressure in the system attains or exceeds thirty pounds per square inch, a condition may be created in which the temperature of the water is considerably in excess of' controls, the temperature of the boiler watershould not exceed 235 F.

For example, with a relief valve setting of thirty pounds gage, it is possible to raise the water temperature to approximately 275 F. which is objectionable. ordinary operating conditions, the boiler water may attain an excessive temperature at a pressure less than that at which the relief valve will open. The relief valve is, therefore, wholly ineffective to protect the system against a high water temperature.

As an illustrative condition, the pressure in the system maybe of the order of twenty pounds gage, but the temperature of the boiler water may be 260 F. or more. Even though the system may be'provided with the usual reducing valve for automatically introducing cold water into the system, such an arrangement would not operate to correct this situation, since these valves are normally set to operate at a pressure of about twelve pounds per square inch.

Overheating presents a serious operating and economic problem in numerous localities because where the service water is indirectly heated by the boiler water to a temperature in excess of 140 F., deposits of lime and sediment are formed rapidly in the coils or tubes of the heater, thus reducing the rate of heat exchange and lowering the temperature of the water available at the service outlets. This liming condition is.

continuously aggravated by recurrent periods ofv overheating. Moreover, in those systems which include a valve in the supply line leading to the radiators, which valve may be motor operated or opened in response to pump pressure under the control of a room thermostat, the temperature rise in the boiler may be accelerated, during periods when the valve is closed,

by the fact that the valve confines the boiler I water to a relatively small space.

. is thermally responsive In other words, under It is, therefore, one object of my invention to provide means for automatically preventing overheating of the water in a 'hot water boiler by utilizing the cold water supply as a cooling agent and providing 'for' a controlled introduction of the cold water into the boiler and an. evacuation of a portion of the hot water.

A further object is to prevent overheating by an arrangement of the character indicated which to the temperature of the boiler water.

A further object is }to prevent overheating by introducing cold water into the system when the temperature of the boiler exceeds a predetermined amountand to discharge a portion of the hot water through a relief valve at the set pressystem and evacuating hot water therefrom are operably responsive to the functioning of a temperature relief valve that is responsive to the temperature of the boiler water.

A further object is to relieve hot water and pressure from a heating system by an arrangement includingtwo, series related, pressure relief valves in which one of the valves is not restrained .by a spring and is adapted to open quickly in response to pressure freed by the other valve.

A further object is to provide an apparatus which may be readily attached to any hot water boiler and which includes controls responsive to the temperature and pressure of the boiler water.

These and further objects of my invention will be set forth in the following specification, refer- Y Fig. 3 is a sectional elevation of a temperature relief'valve employed with my apparatus.

Referring to the drawings, the numeral 68 indicates a hot water heating boiler of the continuously fired type, stoker firing being illustrated in this instance, although hand firing may be employed. From the upper portion of the boiler extends a riser pipe 89 which is connected to one branch of a four-way fitting I8. A second branch of this fitting has-connected thereto one end of a supply pipe II which delivers hot water to any number of radiators (not shown). The system may also include the usual circulating pump and operating controls, but as these details form no part of the invention, they have not been illustrated.

' A third branch of the fitting I has one end of a pipe T2 connected thereto, the opposite end of this pipe being connected to a chamber I3 (see Fig. 2) formed in the lower casing part of a primary relief valve I I. From an intermediate part of the pipe I2 extends a pipe 15 that communicates with a chamber 16 provided in the lower portion of a standard pressure relief valve I1,

this chamber being located below the usual diaphragm 18. As here nafter described. the valve 11 has a piloting relation to the valve 18. Se-' cured to the under side of the diaphragm 18 is a.

sure reducing valve 94. The cover 93-is secured to a casing" and clamped between these parts is a diaphragm 88. From the foregoing, it will be understood that pressure acting in the pipe 92 is also eil'ective against the upper side of the diaphragm 98.

Depending from the under side of the diaphragm 98 is a valve 9! that normally closes a to close the valve 91. The diaphragm 96 is loaded valve 19 which controls flow of water through a poi-.1; 88 formedin the lower portion of the valve 11 and wh ch communicates w th the upper end of a pipe 8|. The valve 19 normally closes the port 88 under the im ulse of a helical spring 82. the lower end of which bears against the upperside of the diaphra m I8v while the o posite end of the s ring abuts the inside of the cover 88. If desired. the valve 19 may be arranged for manual opening by means of the usual handle 84 and linkage connected to the d aphragm I8. The spring 82 is normally set to load the diaphragm at a pressure of thirty pounds per square inch. so that when the boiler pressure exceeds this setting, it will actuate the diaphragm I8 to open the valve 19 and rel eve hot water into the pine 8|. In this connection, it will be understood that boiler pressure is at all times eilective in the riser 89, fitting III, pipes I2 and I5, and the chambers I3 and I6.

Water at boiler pressure which is relieved into theplne 8| passes downwardly into a chamber ,82' included between a cover 83' attached to the casing of the valve H and a diaphragm 88 that is secured between the casing and cover. The upper end of a valve stem 85 is secured to the diaphragm 84 .while the opposite end carries a valve 86 which normally closes a ort-81 formed in the lower wall of the chamber I8. Beneath the diaphragm 84*, a second diaphragm 88 having a smaller area than the diaphragm 88" is secured to the stem 85, the periphery of the diaphragm 88 resting on and being clamped against an annular wall 89 by means of a ring 98, the wall 89 forming a part of the casing for the valve ll.

' At pressures below the relieving pressure of the valve 11, the valve 88 is held in the closed position illustrated in Fig. 2 by means oi boiler pressure operating on the under side of the diaphragm 88, and when valve 88 is opened as hereinafter described, a portion of the hot boiler water is discharged to a drain pipe 9| that is secured to the lower portion of the casing of the valve I8.

One end of a pipe 92 is connected to an intermediate portion of the pipe 8|, while the opposite end thereof communicates with the interior of a cover 98 iormmg part or a standard presby one end of a helical spring I83 withthe opposite end abutting the interior of the cover 93. In accordance with standard practice, it is contemplated that this spring will be set to open the valve 81 when the pressure in the chamber IOI reaches or falls below about twelve pounds per square inch, but this adjustment may be varied as desired.

One branch of a four-way fitting I04 communicates with the chamber |8| and the opposite branch of the same fitting communicates with a chamber I98 which is formed in the casing of the valve I8 between the diaphragms 84* and 88. The other opposite branches of the same fitting are connected, respectively, to the return line 12* from the radiators and to a pipe I86 which delivers the radiator return water, or a mixture thereof with cold water, as hereinafter described, to the lower portion of the boiler.

One end of a dribble pipe I8! is connected to an intermediate part or the pipe 92 while the other end of the pipe I81 may beconnected to the drain pipe 9|. The pipe I81 incorporates a valve I88 which is so adjusted that when water at boiler pressure is delivered into the pipe 8|, the valve I98 will exercise such a throttling effect on the water tending to flow through the pipe I81 that substantially all of the pressure released by the valve 11 will be eflective against the diaphragms 88' and 98. When the valve 'II closes, the pipe I81 slowly relieves the pressur in the chamber 82 and the interior of the cover 93.

The system also provides for relieving the boiler at pressures either above or below the setting of the relief valve 11; this result is accomplished by a device that is responsive to the temperature of the boiler water. Such a device is indicated by the numeral I89 which is a temperature relief valve and is more clearly illustrated in Fig. 3.

This valve comprises a casing IIl whose lower end is formed as a sleeve III that is threaded in one of the branches of the fitting II. The sleeve III is provided with a central passage H2 and the lower end of the sleeve III] has its outer diameter reduced to form a shell H3. Because of the reduced diameter of this shell, an annular passage I is formed between the shell and the fitting branch. Communication between the passages II! and III is provided by means of a plurality of ports II8 formed in the shell H3. The lower end of the shell H8 is closed by a plug H8 and secured thereto is the lower end of a thermostatic element I" of the bellows type whose diameter is less than the diameter of the passage III. Accordingly, hot water flowing through the ports I ll completely bathes the external surface of the bellows. The bellows is filled with alcohol or any of the liquids commonly used in thermostats of this type, the arrangement being such that at the adjusted temperature, the bellows. will elongate and actuate a valve presently described. I

The other end of'the bellows II! is provided with a stem II8 which fits within and abuts the lower end of a multi-winged guide II9 that depends from a valve I20. This valve controls the water flow through a port' I2I within which the in and of itself forms no part of the'invention and is generally of the standard type now commonly employed in the industry. This valve may be adjusted to relieve the boiler at any desired temperature, and for purpose of present discussion, it will be assumed that the valve I20 will be opened by the bellows II! at a boiler temperature of about 235 F., regardless of the pressure then existing in th boiler, i. e., higher or lower than the setting of the relief valve 11.

Hot water flowing through the port I2I is delivered into a chamber I26 and thence through a pipe I21 to the interior of the cover 93 where the boiler pressure becomes effective against the upper surfaceof the diaphragm 96, or in other words, is additive to thepressure exerted on this diaphragm by the spring I03. The result is that the valve 91 isopened by the spring I03 and the boiler pressure acting directly against the valve 91 since the boiler pressure is then equalized on both sides of the diaphragm96 and, if the water pressure in the pipe I02 is higher than the boiler pressure, cold waterwill flow through the port 98int0' the chamber I M and thence to the pipe I06 where itis preheated by mixing with warm water returning from the radiators preliminary to being introduced into the boiler. By this expedlent, it is possible to avoid an excessive temperature differential between the hot water in the upper part and the relatively cold water then entering, the lower part of the boiler. The

boiler is therefore not subjected to excessive racking strains.

Water which is delivered to the interior of the cover 93 by means of the pipe I2I also flows through the pipe 92 into the chamber 82 so that fitting I04 also passes into the chamber I05 and since as soon as this water flows through the valve 94, it becomes subject to boiler pressure,

. valve indicated by the numeral 11.

, eventhough the relief valve I1 is closed, boiler the latter is also effective against the under surface of the diaphragm 84 and the top surface of the diaphragm 88. Boiler pressure'also acts through the chamber I3 against the under side of the diaphragm 88 and hence, under the stated conditions, the forces acting on the respective diaphragms are substantially balanced. However, boile'r pressure acts directly on the valve 86 and unbalances the system of forces operative on the diaphragms sufficiently to open the valve 86 and discharge a portion of the high temperature water from the boiler. In this connection, it will be noted that while the unit pressure is the same on opposite sides of the diaphragm 84, the total force acting on th upper side of the diaphragm is slightly greater than that on the lower side because of the stem 85. However, since the top area of the diaphragm is' large in relation to the cross-sectional area of the stem, it may be considered that the total pressures on opposite sides the diaphragm 84, provision must be made for insuring the closing of this valve when the system is first filled since at this time there is no pressure in the boiler. Under these conditions, the valve 91 is opened by the spring I03 and cold water flows through the port 98 and pipe I06 into the boiler and also into the chamber I05 where its pressure acts upwardly on the diaphragm 84 and downwardly on the diaphragm 88. However, since the diaphragm 84 is larger than the diaphragm 88, the total upward force acting on the stem 85 is greater than the total downward force thereon, so' that this force differential maintains the valve 86 closed during the filling operation. When the system has been filled, the valve 91 is closed by the system pressure acting on the underside of the diaphragm 96 and thereafter until either thevalve I1, or the valve I09, opens, or both, the valve 86 is held closed by the system pressure operative against the underside of the diaphragm 84 The operation of the system is as follows. At a boiler pressure substantially equal to or in excess of the setting of the valve 11, the boiler will be relieved by opening of the valve I9 to thereby cause a sudden discharge of boiler water at boiler pressure into the chamber 82, and against the diaphragm 84 This diaphragm is substantially balanced and the diaphragm 88 is then balanced by oppositely acting forces for reasons already noted and since boiler pressure is efiective in the pipe I06 and chamber I05. The 'valve 86 will therefore be opened by the boiler pressure acting directly. In this action, the relief valve 11 has a and, due to the fact that the operation of the latter is unrestrained by a spring, alarger quantity of water can be evacuated from the boiler in a given period of. time and at a stated pressure than is possible with the standard type of relief When the pressure in the boiler after such an evacuation has fallen below the setting of the valve 11, the latter valve will be closed by the spring 82 and the pressure in the chamber 82 will be relieved through the pipe I0I. The valve 86 will then be returned to the closed position illustrated in Fig. 2 by boiler pressure operating against the under surface of the diaphragm 84 Under the assumed condition of a cold water pressure of about twenty-two pounds per square inch in the pipe I02, no cold water could be admitted to the system even though the valve 91 may be opened by the spring I03 and the boiler pressure acting against the valve 91. This result is due to the fact that at this time the boiler pressure is of the order of thirty pounds or more per square inch. However, it is deemed to be within the scope of this invention to have a pressure available in the pipe I02 higher than the maximum pressure obtainable in the boiler having due regard to the setting of the valve 11. This increased cold water pressure may be ob- I03 and boiler pressure in the chamber IOI to I open the valve 91 and permit the entrance of cold water if the latters pressure is higher than the boiler pressure and to also open the valve 86 and permit the discharge are portion of the hot water from the boiler. It will be understood that under conditions of temperature relief of the boiler, the valve I08 exercises the same throttling action on the water flowing from within the cover 93 to the pipe 8| and which tends to escape through the pipe I01 as obtains when the valve 11 opens. When the valve I09 closes, the pressure within the cover 93 and in the chamber 82 is slowly relieved by the valve I08 and the valve 86 then closes. 'The pipe I01 may also be effective to discharge small quantities of water in relation to the discharge capacity of the valve 88 for small openings of the valves 11 or I09.

The pressure and temperature relief controls above described may operate separately or simultaneously depending upon the operative conditions in the system and may be adjusted for other pressures and temperatures, respectively, than those indicated.

'While the invention has been discussed in connection with hand or stoker fired boilers, it

will be understood that it is not restricted to arrangements of this character. and that these terms are intended to be generally representative of any boiler forming part of a hot water heating system which is subjected to continuous firing.

It should be noted that the diaphragm 88 is merely a convenient arrangement for separating the chambers I3 and I so that sumcientpressure can be built up in the chamber I05 during filling of the boiler to close the valve 86 by this pressure acting against the diaphragm 84 and so that when either or both of the valves 11 and I09 opens, the forces acting on opposite sides of the diaphragm 84 will be substantially equal. It is considered to be within the scope of the invention and the full equivalent of the diaphragm 88 to use a simple dividing wall between the chambers 13 and I05 in conjunction with suitable packing around thestem 85.

I claim:

I 1. In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler comprising first and second valves pressure operated in an opening direction for respectively controlling a cold water supply to the boiler and the discharge of hot water from the'boiler, and thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening both valves by applying boiler pressure thereto.

2. In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler comprising first and second valves pressure operated in an opening direction for respectively controlling a cold water supply to the boiler and the discharge of hot water from the-boiler, thermostatic valve means responsive to and opening at a. predetermined temperature of the boiler water tor opening both valves by applying boiler pressure thereto, "and ing with a drain, a relief valve having a stem nation of a boiler, and means for preventing overheating of the boiler comprising a diaphragm, a valve secured to one side thereof for controlling a cold water supply to the boiler, a casing having an intermediate chamber communicating with the boiler and the valve side of the diaphragm and including two movable wall portions, a second chamber communicating with the opposite side of the diaphragm and including one of the wall portions, a third chamber communicating with the boiler and including the other wall portion and a valve port communicatconnected to both wall portions for controlling flow through the port, boiler pressure acting against said one wall portion to normally close the relief valve, and thermostatic'valve means responsive to andopening at a predetermined temperature of the boiler water for opening the diaphragm and relief valves by applying boiler pressure thereto, the pressure on opposite sides of the wall portions being substantially balanced.

4. In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler. comprising a diaphragm, a valve secured to one side thereof for controlling a cold water supply to the boiler, a casing having an intermediate chamber communicating with the boiler and the valve side of the diaphragm and provided with a large and a small diaphragm located in opposed relation, a second chamber communicating with the opposite side of the first named diaphragm and including the large diaphragm, 'a third chamber communicating with the boiler and including the small diaphragm and a valve port communicating with a drain, a relief valve having a stem connected to the large and small diaphragms for controlling flow through the port, boiler pressure acting against the large diaphragm to normally close the relief valve, and thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening the diaphragm and relief valves by applying boiler pressurethereto, the boiler pressure on opposite sides of the large and small diaphragms, respectively, being substantially balanced when the relief valve is opened and cold water discharged by the diaphragm valve during filling of the boiler acting on the intermediate chamber side of the large diaphragm to close the relief valve.

5. In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler comprising separate boiler pressure operated means for respectively controlling a coldwater supply to the boiler and the discharge of hot water from the boiler, and valve means responsive to and opening at a predetermined temperature of the boiler water for opening said separate meansby applying boiler pressure thereto.

6.' In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler comprising a valve controlling a cold water supply to the boiler, a reliei valve for discharging hot water to a drain, and thermostatic means responsive to a predetermined temperature of the boiler water, both valves opening in response to the actuation of the thermostatic means.

7. Apparatus for preventing overheating of the boiler of a heating system comprising a casing chamber constituting a cold water supply and the other being arranged for connection to a boiler, a valve controlling communication between the chambers, a relief valve opening to a drain for evacuating a portion of the hot water in the boiler, and means responsive to a predetermined temperature of the boiler water, both valves opening in response to the actuation of the means.

8. In a hot water heating system, the .combination of a boiler, and means for preventing overheating of the boiler comprising a diaphragm,

a valve secured to one side thereof for controlling a cold water supply to the boiler, a casing having an intermediate chamber communicating with the boiler and the valve side of the diaphragm and including two movable wall portions, 9. second chamber communicating with the opposite side of the diaphragm and including one of the wall portions, a third chamber communicating with the boiler and including the other wall and a valve port opening to a drain, a relief. valve having a stem connected to both wall portions for controlling flow through the port, boiler pressure acting against said one wall portion to normally close the relief valve, thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening the diaphragm and relief valves by applying boiler pressure thereto, the pressure on opposite sides of the wall portions being substanagainst the large diaphragm to normally close the relief valve, and thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening the diaphragm and relief valves by applying boiler pressure thereto, the pressure on opposite sides of the large and small diaphragms being substantially balanced when the thermostatic means opens and the cold water discharged by the diaphragm valve acting on the intermediate chamber side of the large diaphragm to close the relief valve during filling of the boiler.

11. In a hot water heating system, the combination of a boiler, and means for relieving the boiler at a predetermined pressure comprising a pilot relief valve boiler pressure operated in an opening direction at said predetermined pressure and spring actuated to closure, a primary relief valve having an intermediate chamber communicating with the boiler and provided with two movable wall portions, a second chamber communicating with the discharge side of the pilot valve and including one of the wall portions, 9. third chamber communicating with the boiler and including the other wall portion and a valve port opening to a drain, and a valve element having a stem connected to both wall portions for-controlling the flow through the port, boiler pressure acting against tne intermetially balanced when the thermostatic means opens, and a bleeding port for slowly reducing the pressure in the second chamber when the thermostatic means closes.

9. Apparatus for preventing overheating oi the boiler of a heating system comprising a diaphragm, a valve secured to one side thereof for controlling a cold water supply to the boiler, a casing having an intermediate chamber communicating with the boiler and the valve side of the diaphragm and including two movable wall portions, a second chamber communicating with the opposite side of the diaphragm and including one of the wall portions, a third chamber communicating with the boiler and including the other wall portion and a valve port opening to a drain, a relief valve having a stem connected to both wall portions for controlling flow through the port, boiler pressure acting against said one wall portion to normally close the valve, and thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening the diaphragm and relief valves by applying boiler pressure thereto, the pressure on opposite sides of the respective wall portions being substantially balanced when the thermostatic means opens.

10. Apparatus for preventing overheating of diate chamber side of said one wall portion to normally move the valve element to a closed position, the boiler pressure on opposite sides of the, respective wall portions being substantially balanced when the pilot valve opens and the valve element being opened by boiler pressure acting directly thereagainst.

12. In a hot Water heating system, thecombination of a boiler, and means for relieving the boiler at a predetermined pressure comprising a pilot relief valve boiler pressure operated in an opening direction at said predetermined pressure and spring actuated to closure, and a primary relief valve having an intermediate chamber communicating with the boiler and provided with a large and a small diaphragm located in opposed -relation, a second chamber communicating with the discharge side of the pilot valve and the boiler of a heating system comprising a dia f small diaphragm and a valve port opening to a drain, a relief valve having a stem-connected to the large and small diaphragms for controlling flow through the port, boiler pressure acting including the large diaphragm, a third chamber I communicating with the boiler and including the small diaphragm and a valve port opening to a drain, and a valve element having a stem connected to both di'aphragms for controlling flow through the port, boiler pressure acting against the intermediate chamber side of the large diaphragm to normally hold the valve element in closed position and the pressure on opposite sides of the respective diaphragms being substantially balanced when the pilot valve opens to thereby open the valve element by boiler pressure acting directly thereagainst, theelement being closed during filling of the boiler by pressure against the intermediate chamber side of the large diaphragm.

13. In a hot water heating system, the combination of a boiler, and means for relieving the boiler at a predetermined pressure comprising a pair of series related valves, one valve being spring actuated to closure and opening at said predetermined pressure and the other valve comprising an intermediate chamber communicating with the boiler and including a pair of oppositely disposed diaphragms, a second chamber communicating with the discharge side of the first named valve and including one of the diaphragms, and a third chamber communicating tive diaphragms being substantially balanced when the first named valve is opened to thereby open the valve element by boiler pressure acting directly thereagainst.

14. Apparatus for relieving a hot water heating boiler at a predetermined pressure compris-,

ing a pilot relief valve operable in an' opening direction at and by said predetermined pressure and spring actuated to closure,'and a primary relief valve having an intermediate chamber communicating with the boiler and provided with a pair of movable wall portions, a second chamber communicating with the discharge side of the pilot valve and including one of the wall portions, 9. third chamber communicating with the boiler and including the other wall portion and a valve port opening to a drain, and a valve element having a stem connected to both wall'portions for controlling flow through the port, boiler pressure acting against the intermediate chamber side of the first named wall portion to normally hold the element in closed position and the pressure on opposite sides of the respective wall portions being substantially balanced when the pilot valve opens to thereby open the valve element by boiler pressure acting directly thereagainst.

15. Apparatus for relieving a boiler ata predetermined pressure comprising a pilot relief valve operable in an opening direction at and by said predetermined pressure and spring actuated to closure, and a primary relief valve having an intermediate chamber com=- municating with the boiler and including a large and a small diaphragm located in opposed relation, a second chamber communicating with the discharge side of the pilot valve and includin the large diaphragm, a third chamber communieating with the boiler and including the small diaphragm and a valve port opening to a drain, and a valve element having a stem connected to both diaphragms for controlling flow through i the port, boiler pressure acting against the intermediate chamber side'of the large diaphragm to normally hold the element in closed position and pressure on opposite sides of the respective diaphragms being substantially balanced when the pilot valve opens to thereby open the valve element by boiler pressure acting directly thereagainst, the element being closed during filling of the boiler by pressure against the intermediate chamber'side of the large diaphragm.

16. In a hot water heating system, the combination of a boiler, and means for preventing overheating of the boiler by introducing cold water into and discharging a portion of the hot water from the boiler at a predetermined pressure comprising a valve controlling a cold water supply to the boilerand boiler pressure operated in an opening direction, a pilot relief valve onerable in an opening direction at and by said predetermined pressure and spring actuated to closure, and a primary relief valve having an intermediate chamber communicating with the boiler and including two movable wall portions, a second chamber communicating with the discharge side of the pilot valve and including one hot water heating of the wall portions, a third chamber communicating with the boiler and including the other wall portion and a valve port opening to a drain,

a valve element having a stem connected to both wall portions for controlling flow through the port, boiler pressure acting against the intermediate chamber side of the said one wall portion to normally hold the element in closed position and the pressure on opposite sides of the respective wall portions being substantially balanced when the pilot valve opens to thereby open the element by boiler pressure acting directly thereagainst. Y

17. Apparatus for relieving a hot water heatlog boiler at a predetermined pressure comprising a pilot reliefvalve operable in an opening direction at and by said. predetermined pressure and spring actuated to closure, and a primary relief valve having an intermediate chamber communicating with the boiler and provided with a pair of movable wall portions, a second chamber communicating with the discharge'side of the pilot valve and including one of the wall portions, a third chamber communicating with the boiler and including the other wall portion and a valve port opening to a drain, and a valve element having a stem connected to both wall portions for controlling flow through the port, boiler pressure acting against the intermediate chamber side of the first named wall portion to normally hold the element in closed position and the pressure on opposite sides of the respective wall portions beingsubstantially balanced when the pilot valve opens to thereby open the valve element by boiler pressure acting directly thereagainst, the second chamber including a bleeding port for slowly relieving the pressure therein after the pilot valve closes.

18. Apparatus for preventing overheating of a hot water heating boiler comprising a pilot relief valve operable at a predetermined boiler pressure, a temperature relief valve opening at a predetermined temperature of the boiler water, and a primary relief valve operably related to the discharge sides of the pilot and temperature relief valves and opening to relieve a portion of the boiler water to a drain when either or both of the last two named valves operate.

19. Apparatus for preventing overheating of a hot water heating boiler comprising a pilot relief valve opening at a predetermined boiler pressure, a temperature relief valve opening at a predetermined temperature of the boiler water, and a primary relief valve operable related to the discharge sides of the pilot and temperature relief valves and having a part pressure operated in an opening direction to relieve a portion of the boiler water to a drain when either or both of the two last named valves operate.

20. Apparatus for preventing overheating of a hot water heating boiler comprising a pilot rel ef valve opening at a predetermined boiler pressure, a temperature relief valve opening at a predetermined temperature of the boiler water, anda primary relief valve operably related to the discharge sides of the pilot and temperature relief valves and pressure operated in an opening direction to relieve a portion of the boiler water to a drain when either or both of the two last named valves operate, and means carried by the primary valve responsive to boiler pressure direction at and by said predetermined pressure and spring actuated to closure, and'a primary relief valve having an intermediate chamber communicating with the boiler and provided with a movable wall portion, a second chamber communicating with the discharge side of the pilot valve and including the wall portion, a third chamber communicating with the boiler and including a valve port opening to a drain and separated from the intermediate chamber by a dividing wall, and a valve element having- 22. Apparatus for preventing overheating of the boiler of a heating system comprising a diaphragm, a valve secured to'one side thereof for controlling a cold water supply to the boiler, a casing having an intermediate chamber communicating with the boiler and the valve side of the diaphragm and provided with a movable wall portion, a second chamber communicating with the opposite side of the diaphragm'and including the wall portion,a third chamber communicating with the boiler and including a valve port opening to a drain and separated from the intermediate chamber by a dividing wall, a valve element having a stem extending through the dividing-wall for connection to the wall portion for controlling flow through the port, boiler pressure acting against the wall portion to noron opposite sides of the wall portion being substantially balanced when thethermostatic means opens.

mally close the valve, and thermostatic valve ment by applying pressure thereto, the pressure 23. Apparatus for preventing overheating of a hot water heating boiler comprising first and second valves pressure operated in an opening direction for respectively controlling a cold water supply to the boiler and the discharge of hot water from the. boiler, and thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening both valves by applying boiler pressure thereto.

1 24. Apparatus for preventing overheating of a hot water-heating boiler comprising first and second valves pressure operated in an opening direction for respectively controlling a cold water supply to the boiler and the discharge of hot water from the boiler, thermostatic valve means responsive to and opening at a predetermined temperature of the boiler water for opening both valves by applying boiler pressure thereto, and means responsive toboiler pressure for returning the second valve to closed position.

25. Apparatus for preventing overheating oi a hot water heating boiler comprising separate boiler pressure operated means for respectively controlilng a cold water supply to the boiler and the discharge of hot water from the boiler, and valve means responsive to and opening at a predetermined temperature of the boiler water for opening said separate means by applying boiler pressure thereto. a

26. In a hot water heating system having a boiler, apparatus for preventing overheating of the boiler comprising a valve controlling a cold water supply to the boiler, a relief valve for discharging hot water to a drain, and thermostatic means immersed in and responsive to a predetermined temperature of the boiler water, both valves opening in response to the actuation of the thermostatic means.

ROBERT EDWIN MOORE. 

